1. Technical Field
The present disclosure relates generally to ablation electrode systems and, more particularly, to systems, devices and methods for positioning and placing multiple electrodes in a target surgical site.
2. Background of Related Art
The use of radiofrequency electrodes for ablation of tissue in a patient's body is known. In a typical situation, a radiofrequency electrode comprising an elongated, cylindrical shaft with a portion of its external surface insulated is inserted into the patient's body. The electrode typically has an exposed conductive tip, which is used to contact body tissue in the region where the heat lesion or ablation is desired. The electrode is connected to a radiofrequency power source, which provides radiofrequency voltage to the electrode, which transmits the radiofrequency current into the tissue near its exposed conductive tip. This current usually returns to the power source through a concentric electrode in a bipolar system or through a reference electrode in a monopolar system. The reference electrode may comprise a large area conductive contact or pad connected to an external portion of the patient's body.
In some applications, e.g., wedge resections (segmentectomies) or tumor ablation procedures, multiple electrodes are inserted into the body in an array or partial array to enlarge ablation volumes and specifically define resection areas. For example, in some particular applications, arrays of high frequency electrodes are inserted into tumors and energized to create an ablation volume depending upon the particular positioning of the electrodes. The electrodes are typically placed in a dispersed fashion throughout the tumor volume to cover the tumor volume with uniform heat, typically above about 45° C. The electrodes may be sequentially applied with high frequency voltage so that each electrode heats in sequence its neighboring tissue and then shuts off. Then, the next electrode does the same in a time series. This sequence of cycling the voltage through the electrodes continues at a prescribed frequency and for a period of time until the tumor is ablated.
Desirably, a configuration of radiofrequency electrodes, which can accomplish ablation in the range of 4 to 6 cm diameter or greater for the purpose of adequately treating large cancerous tumors in the body are necessary to effectively destroy the tumor and combat cancerous cells from spreading. It is further necessary that such an electrode system involve a simple geometry, reduced numbers of tissue insertions, facilitate planning of needle placement, and facilitate planning of heat ablation geometry and distribution. Typically, an introducer is provided for this purpose and to facilitate the insertion of a “cluster” of electrodes into the body for performing tissue ablation. The introducer includes a body portion including one or more holes formed therein for selectively receiving a respective elongate shaft of the electrodes therethrough. The holes of the introducer orient and space each electrode relative to one another according to the geometry of the introducer.